Hygroscopic Nature\nof Lithium Ions: A Simple Key to\nSuper Tough Atmosphere-Stable Hydrogel Electrolytes

Gel electrolytes have emerged as a versatile solution\nto address\nnumerous limitations associated with liquid electrolytes in electrical\nenergy storage (EES) devices, in terms of safety, flexibility, and\naffordability. Aqueous gel electrolytes, in particular, exhibit exceptional\nfeatures by offering one of the highest ion solvation capacities and\nionic conductivities. The two main challenges with hydrogel electrolytes\nare their easy freezing at subzero temperatures and rapid dehydration\nunder open conditions, leading to the failure of the EES device. In\nresponse, we present an uncomplicated and quick-to-make hydrogel electrolyte\nsystem offering impressive mechanical properties (205.5 kPa tensile\nstrength, 2880 kJ/m<sup>3</sup> toughness, and 3030% strain at the\nbreak), along with antifreezing and antiflammability attributes. Notably,\nthe hydrogel electrolyte demonstrates high ionic conductivity and\nsuperior performance in supercapacitor cells over a wide range of\ntemperatures (−40 to 80 °C) and under various deformations.\nThe hydrogel electrolyte maintains its capabilities under open conditions\nover an extended period of time, even at 50 °C, showcased by\npowering a wristwatch. The atmospheric stability of the hydrogel electrolyte\ndemonstrated in this study introduces promising prospects for the\nfuture of EES devices spanning from production to end-user consumption.